Further Information

• Summary of von Willebrand disease

  von Willebrand disease (vWD) is a heterogeneous and complex bleeding disorder affecting about 1/100 people. It is caused by a deficiency or a defect in von Willebrand factor (vWF) and is the most common cause of excessive bleeding or bruising in the general population. Despite this it is considered to be the most widely under diagnosed of the bleeding disorders.

  vWF is synthesised and stored predominately in vascular endothelial cells, and is also synthesised in megakaryocytes and stored in the platelets. When vWF is first released into the plasma it is in the ultra-large form (multimers). These ultra-large multimers are quickly processed further into smaller multimers, as a result of cleavage by the protease ADAMTS-13 (A Disintegrin And Metalloprotease with ThromboSpondin repeats), resulting in a reduction in size of the multimers. When ADAMTS13 levels are decreased, ultra-large multimers appear in the circulation and cause platelet aggregation in vivo, often resulting in thrombotic thrombocytopenic purpura (TTP).

  Screening tests alone are not sensitive enough to exclude vWD, indeed it is not uncommon for the APTT to be within the normal range. It is possible to distinguish between vWD types by measuring vWF ristocetin cofactor activity (vWF:Rco), vWF collagen binding activity (vWF:CB), vWF antigen (vWF:Ag) and FVIII:c. The correct diagnosis is important because treatment is dependent on the subtype of vWD.

  Laboratory values and clinical symptoms can vary considerably, even in the same individual. Plasma vWF levels are influenced by blood group, race, age, pregnancy, pathological conditions, exercise, stress and trauma, so establishing a definitive diagnosis of vWD is often difficult, therefore follow-up testing is advised to confirm diagnosis.

  For more detailed information on von Willebrand disease, please download our vWF disease factsheet here: vWF Factsheet

  Product Information

  The Axis-Shield von Willebrand Factor activity test is a quantitative direct enzyme-linked immunosorbent assay (ELISA) for the detection of vWF:Rco activity in citrated human plasma.

  The Vital^TM CBA ELISA is for the detection of Collagen Binding Activity in citrated human plasma.

  The American Diagnostica range includes FVIII:c antigen, together with kits for ADAMTS13 antigen and antibody in ELISA format. The ADAMTS13 activity test is available as a functional fluorescence resonance energy transfer (FRET) assay.

  
  

  Ordering Information

  ADI-885*                   IMUBIND® vWF Activity ELISA, 96 microwell plate

  VD-4000040              Collagen Binding Assay, 12 x 8 tests

  ADI-884                    CON IMUBIND® Factor VIII ELISA, 12 x 8 tests

  ADI-811                    IMUBIND® ADAMTS13/FXI Complex ELISA, 96 microwell plate

  ADI-812                    ACTIFLUOR™ ADAMTS13 Activity Assay, 48 tests

  ADI-813                    IMUBIND® ADAMTS13 ELISA, 96 microwell plate

  ADI-813H (half size)   IMUBIND® ADAMTS13 ELISA, 3 x 16 strip wells

  ADI-814                    IMUBIND® ADAMTS13 Autoantibody ELISA, 96 microwell plate

  ADI-814H (half size)   IMUBIND® ADAMTS13 Autoantibody ELISA, 3 x 16 strip wells

  * Now manufactured by American Diagnostica Inc. Previous product code UK-FVWF200.